xhash: Create Hash Table for Generic States

In kota7/tictactoe: Tic-Tac-Toe Game

Description

This function creates an xhash object, extended version of hash. While hash accepts only strings as indices, xhash can deal with generic index variables, termed as "state".

Usage

xhash(convfunc = function(state, ...) state, convfunc_vec = function(states,
  ...) unlist(Map(convfunc, states, ...)), default_value = NULL)

Arguments

convfunc	function that converts a state to a key. It must take a positional argument state and keyword arguments represented by ..., and returns a character.
convfunc_vec	function for vectorized conversion from states to keys. This function must receive a positional argument states and keyword arguments ... and returns character vector. By default, it vectorizes convfunc using Map. User may specify a more efficient function if any.
default_value	value to be returned when a state is not recorded in the table.

Value

xhash object

See Also

hash-ops, vectorized-hash-ops

Examples

h <- xhash(convfunc = function(state, ...) paste0(state, collapse='-'))

# insert
h[c(1, 2, 3)] <- 100
h[matrix(1:9, nrow=3, ncol=3)] <- -5

# retrieve
h[c(1, 2, 3)]
h[matrix(1:9, nrow=3, ncol=3)]
h[1:9]          # equivalent as above, due to conversion to a same key
h[c(3, 2, 1)]   # this is undefined

# delete
h[c(1, 2, 3)] <- NULL

# vectorized operations
## insert
setvalues(h, list(1:2, 1:3), c(9, 8))
## retrieve
getvalues(h, list(1:9, 1:2, 3:1))
## delete
setvalues(h, list(1:9, 1:3), NULL)

kota7/tictactoe documentation built on May 20, 2019, 1:11 p.m.